A1232: Ultra-Sensitive, Hall-Effect Speed and Direction Sensor with TPOS


The A1232 is a highly sensitive, temperature stable magnetic sensing device ideal for use in ring magnet based speed and direction systems in harsh automotive and industrial environments. It contains two bipolar, Hall-effect switches precisely arranged 1.63 mm apart. The switch outputs are thus in quadrature when interfaced with the proper ring magnet design. Internal logic processes the resulting digital signals to derive speed and direction information that is presented at the device’s outputs, OUTPUT A and OUTPUT B.

The A1232 is designed for demanding, high performance motor commutation applications. The Hall elements are photolithographically aligned to better than 1 µm. Accurately locating the two Hall elements eliminates a major manufacturing hurdle encountered in fine-pitch applications. The A1232 also has true power-on state (TPOS), the ability to detect when it is in the hysteresis band, beyond BOP, or below BRP at power-on. This provides reduced angle accuracy error due to missed start-up edges.

Post-assembly factory programming at Allegro provides sensitive, symmetrical switch points for both switches. Extremely low-drift amplifiers maintain this symmetry. The Allegro® patented, high-frequency chopper-stabilization technique cancels offsets in each channel and allows for increased signal-to-noise ratio at the input of the internal comparators. This leads to stable operation across the operating temperature and voltage ranges and industry leading jitter performance.

An on-chip regulator provides a wide operating voltage range. The A1232 is packaged in a plastic 8-pin surface mount TSSOP (LE). This gull wing style package is optimized for the extended temperature range of –40°C to 150°C. It is lead (Pb) free and RoHS-compliant, with a 100% matte tin plated leadframe.

Top Features

  • Senses speed and direction of ring magnets
    • Two matched bipolar Hall-effect switches on a single substrate
    • True Power-On State (TPOS): Recognizes hysteresis region at power-on
  • Superior temperature stability
  • Internal regulator for 3.3 to 24 V operation
  • Symmetrical, high sensitivity switch points
  • Automotive grade
    • Solid-state reliability
    • Integrated ESD diodes
    • Robust structures for EMC protection
    • Short-circuit protected outputs
    • Reverse battery protection
    • –40°C to +150°C operating range

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Part Composition /
RoHS Data
Comments Samples Check Stock
A1232LLETR-T 8-lead TSSOP -40°C to 150°C Yes View Data Contact your
local sales rep
Distributor Stock

Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of Allegro’s product can reasonably be expected to cause bodily harm.



Insight and Innovations